1. Field of the Invention
The subject invention relates to a clamping mechanism for an adjustable steering column assembly.
2. Description of the Prior Art
Vehicles often include a steering column assembly that is adjustable in at least one of a telescoping direction and a tilt (rake or pivot) direction. The steering column assembly typically includes a column jacket. The column jacket may include an upper jacket and a lower jacket, with the lower jacket in sliding engagement with the upper jacket along a longitudinal axis to permit adjustment of the steering column assembly in the telescoping direction. A mounting bracket mounts the column jacket to the vehicle, and typically defines a tilt axis about which the steering column assembly rotates to permit adjustment of the steering column assembly in the tilt direction. Typically, the steering column assembly further comprises a rake bracket. A clamping mechanism couples the column jacket to the rake bracket in a desired position. The clamping mechanism couples the column jacket to the rake bracket and is moveable between a lock position and a release position. The lock position restrains movement of the column jacket in the tilt direction and the telescoping direction relative to the rake bracket, and the release position permits movement of the column jacket in the tilt direction and the telescoping direction relative to the rake bracket.
There are several different styles of clamping mechanisms utilized in the adjustable steering column assembly. One suitable type of clamping mechanism is disclosed in U.S. Patent Application Publication No. 2006/0196302 A1 to Hochmuth et al. (the '302 application). The clamping device in the '302 application comprises a static plate and a dynamic plate. The static plate defines a plurality of static lifting ramps and is configured for attachment to the adjustable steering column assembly. The dynamic plate is in spaced parallel relationship to the static plate and is rotatable relative to the static plate about a transverse axis between a lock position and a release position. The transverse axis extends perpendicular to the dynamic plate and the static plate. The dynamic plate defines a plurality of dynamic lifting ramps. Each of the dynamic lifting ramps opposes one of the static lifting ramps to define opposing pairs of ramps.
The clamping mechanism further comprises a plurality of rollers. Each of the rollers is disposed within one of the opposing pairs ramps, and is moveable between a raised position and a recessed position within the opposing pair of ramps. The rollers are disposed in the raised position when the dynamic plate is in the lock position to bias the dynamic plate outward along the transverse axis away from the static plate. The rollers are disposed in the recessed position when the dynamic plate is in the release position to permit axial movement of the dynamic plate along the transverse axis toward the static plate.
The dynamic lifting ramps are arranged on an inner surface of the dynamic plate circumferentially along a continuous circular alignment concentric with the transverse axis, and the static lifting ramps are likewise arranged on an outer surface of the static plate circumferentially along a continuous circular alignment concentric with the transverse axis. Accordingly, the rollers are free to slip down the static lifting ramps and the dynamic lifting ramps without any corresponding rotational movement of the dynamic plate relative to the static plate, thereby releasing the clamping pressure provided by the clamping mechanism.